TFII-I is a multi functional, signal dependent transcription factor that is implicated in the regulation of many genes. The purpose of this work is to determine its role in the immune system specifically in the Immunoglobulin heavy chain (IgH) locus of B-cells. It was previously shown in vitro that two TFII-I family members bound to a region of the IgH promoter named Downstream Immunological Control Element (DICE). However, these family members, TFII-I and BEN, have opposing transcriptional functions. Specific goals of the project include;determining how TFII-I and BEN transcription factors are recruited to the rearranged IgH promoter in vivo. This will be accomplished by the use of EMSA analysis with TFII-I and BEN mutant proteins, chromatin immunoprecipitation of the DICE region using TFII-I and BEN antibodies and functional assays to determine the potential role that these factors play. Because the IgH locus is also regulated at the level of subnuclear positioning, by virtue of their distinct function and subnuclear localization, TFII-I and BEN may be involved in this movement. If so, then 3D-FISH analysis of both knockdown and wild type B-cells might determine their potential role on the movement of the locus.